A night of drinking and drug abuse took a horrifying turn in The Bronx when an ex-con allegedly snapped at his legally blind gal pal, butchered her and threw her from a roof into an alley, police sources said yesterday.

Duvale Stevens, 36, slept in Andrea Hurd’s bed after her murder at 2:45 a.m. Wednesday in her Mott Haven apartment, the sources said.

He allegedly confessed to stabbing her in the neck and chest with a kitchen knife and dropping her five stories. On parole for attempted drug sale, he’s charged with murder and criminal possession of a weapon.